GPS for Dummies.pdf - Engineering Surveyor

258Part III: Digital Mapping on Your Computer If your scanned map has a ruler printed on the map that shows distance(for example, in one-mile increments), select Distance Display from theView menu. This allows you to measure the distance of a line that youdraw on the map. The length of the map’s ruler should match whateverdistance is shown when you measure it. Move the cursor over a feature on the map with known coordinates. (Thecoordinates can come from a GPS receiver, another mapping program, ora gazetteer.) The cursor coordinates in OziExplorer should be relativelyclose to the known coordinates of the feature.If any coordinate or distance numbers seem significantly off, there’s likely aproblem with your calibration. To address this, do the following:1. Choose Check Calibration of Map from the File menu.This displays the calibration setup window.2. In the calibration setup window, verify or change calibration data.• Make sure that your calibration points are in the proper locationon the map and have the correct coordinates.• Try changing the map datum and/or projection to different values.3. Click Save to save the results to a different MAP file.The newly calibrated map is loaded and is displayed onscreen.4. Check whether the calibration is more accurate.If the calibration isn’t sufficiently accurate, repeat these steps.